The present invention relates to downhole apparatus and methods. More particularly the present invention relates to remote setting of a sealing element in a downhole apparatus.
Some packoff devices allow signals to pass through the casing, but most include a hole in the casing to pump tubing pressure into a setting chamber to set the packoff or operate the device. Even when holes are not provided for pressure reasons, a hole may be required to allow for an electronic feedthrough, which provides a potential leakage path between an interior and an exterior of the casing. Such hole may be drilled through the casing and machined with or without a thread. The thickness of the casing wall precludes an effective metal to metal seal to be used or designed. Such hole in the casing may be undesirable as it may connect to a sealed chamber using elastomeric and/or thermoplastic seals on the outside of the casing. If these seals become compromised, then a potentially very consequential leak from the interior of the casing to the annulus may occur.